Anyone else have trouble with damp sheds or workshops?
Been having condensation issues with my Keter shed that I use to store a couple of my bikes in.
I've been happy with the shed, but I get condensation dripping from the plastic roof, probably a combination of plastic and it being black.
When the sun eventually comes out the roof heats up causing condensation to form and drip on the bikes at times.
Last year I fitted two vents, one low level and one high to create air flow, but it didn't really help.
I did a bit of research and this is what I came up with or copied from others.
I've just installed a large car radiator fan rigged up to a couple of solar panels and a controller, timer and speed controller.
It's a bit over the top, but hopefully it'll keep the damp out of the shed.
Total cost was about £100, I upgraded to two panels as I want it to work all year round including overcast days.
I hadn't planned it but a side effect is I can now maintain bike batteries over the winter. 
Shed solar powered ventilation

Nope.  I have a couple of  keter sheds.  One housing a couple of pushbikes, the other housing the missuses gardening stuff.  Cannot ever say I noticed any damp problems.

I put a dehumidifier in a similar situation, garage with steel ceiling, but I have line power. I only really use it in the summer when the humidity really gets bad, southern USA. Totally solved the issue. Maybe a heavy extension cord might do ya? Three or four bags of DampRid can help too.